This seems fairly simple, but it's taken up quite a bit of my time.

 

I'd like to render an item on the game's main hud, but this code isn't working:

 

package x.thealphaelement.eventhandlers;

import net.minecraft.client.Minecraft;
import net.minecraft.client.gui.Gui;
import net.minecraft.client.gui.GuiIngame;
import net.minecraft.client.renderer.entity.RenderItem;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraftforge.client.event.RenderGameOverlayEvent;
import net.minecraftforge.client.event.RenderGameOverlayEvent.ElementType;
import net.minecraftforge.event.EventPriority;
import net.minecraftforge.event.ForgeSubscribe;

import org.lwjgl.opengl.GL11;

import x.thealphaelement.TheAlphaElement;

public class OverlayEventHandler extends Gui {

protected Minecraft mc;
protected static RenderItem itemRenderer = new RenderItem();

public OverlayEventHandler(Minecraft mc) {
	super();

	this.mc = mc;
}

  @ForgeSubscribe(priority = EventPriority.NORMAL)
  public void onRenderExperienceBar(RenderGameOverlayEvent event)
  {
   
    if(event.isCancelable() || event.type != ElementType.EXPERIENCE)
    {      
      return;
    }

    EntityPlayer player = this.mc.thePlayer;
    
    int redPotionCount = getItemCount(player, TheAlphaElement.redPotion);
    ItemStack vendorStack = new ItemStack(TheAlphaElement.redPotion);
   	   
	this.mc.renderEngine.bindTexture("/mods/TheAlphaElement/textures/items/redPotion.png");
        this.drawTexturedModalRect(40, 50, 0, 0, 18, 18);
    
    this.drawString(mc.fontRenderer, Integer.toString(redPotionCount), 30, 31, 16777215);
   
  }
  
  /**
	 * Counts the number of the specified item in the player's inventory.
	 * @param player - The player's inventory to check.
	 * @param itemStack - The ItemStack to look for.
	 * @return The number of items that match.
	 */
public int getItemCount(EntityPlayer player, Item item) {
	ItemStack thisStack;
	int count = 0;

	int i;
	for(i = 0; i < player.inventory.getSizeInventory(); ++i) {
		thisStack = player.inventory.getStackInSlot(i);
		if(thisStack != null && thisStack.itemID == item.itemID) {
			count += thisStack.stackSize;
		}
	}

	return count;
}


}

 

The above code DOES work if I switch the texture to a different .png that doesn't have transparency.  Is transparency the issue?

Alright, figured it out. 

 

The texture bound to the renderEngine (using this.mc.renderEngine.bindTexture()) must be a 256x256 texture.  I made such a large, transparent texture (an item sheet) and pasted my item's icon into the top left 32x32 16x16 part of it (the first "slot" on the item sheet), and the icon renders properly on the main HUD now.

 

This seems like a bit of a roundabout way to do it... though I do suppose it will be useful to have this item sheet if I need to do many such things later with the mod.

 

If anyone knows of a more direct way, to do it, I'd be happy to hear it.

 

Edit: Added a bit of elaboration and also changed 32x32 to 16x16, for anyone else needing info on this issue.  32x32 is slightly inaccurate; you'll most likely want to use 16x16 for your icons.